The concept of a residential gateway device is gaining more attention from content service providers, such as IPTV or DVB operators, as an option for minimizing the number of set top boxes (STBs) in a subscriber's home (typically a significant capital expense for the service provider). A residential gateway is a class of devices that can share content with other playback devices already in the home. Examples of devices that can act as residential gateways include (but are not limited to) set top boxes (STBs) and digital video recorders (DVRs). The Digital Living Network Alliance (DLNA) device communication architecture enables device and content discovery within a local area network and subsequent streaming, or possibly copying of content, between devices connected via a local network. DLNA enables such a business model by treating a single residential gateway as a Digital Media Server (DMS), which receives the service provider's content and redistributes it within the home to client devices called Digital Media Players (DMP) or Digital Media Renderers (DMR). Examples of DMPs and/or DMRs include (but are not limited to) network connected consumer electronics devices such as televisions, game consoles and optical disk players, personal computers, mobile phones, and tablet computers. In addition to using the residential gateway to distribute stored content via the local network, the residential gateway can also be used to distribute linear content being received live, with or without the intermediate recording step.
For premium content, DLNA provides a mechanism to signal content protection in the Content Directory Service (CDS) via a standardized Internet media type (also referred to as a Multipurpose Internet Mail Extensions type or MIME type). By default, DLNA supports Digital Transmission Content Protection for Internet Protocol (DTCP-IP) link protection that is independent of the conditional access/digital rights management technology (CA/DRM) used to deliver the content to the residential gateway by the content service provider. DTCP-IP is a “link protection” technology that protects audiovisual content, when transmitted between digital entertainment products, against unauthorized copying, interception and tampering within the home, while ensuring that content can be viewed and copied on home networked devices. DTCP-IP enables audiovisual content to be transmitted, in an encrypted form, only to those devices within a local network that have authenticated compliance with DTCP. When DTCP-IP is used, the DMS terminates the service provider's CAS/DRM, decrypts the content and re-encrypts it for further distribution within the home over DTCP-IP. CAS/DRM systems typically deliver content with a set of Copy Control Information (CCI) and Usage Rules. DLNA via DTCP-IP has a very limited mechanism to propagate this control, namely using the DTCP-IP Protect Content Packet Usage Rules (PCP-UR) field and/or the DTCP Descriptors. These may suffice for simple streaming to other devices in the home but are not adequate for copying or moving content within the home domain. Moreover, interpretation of the CCI bits can be problematic when content broadcast as “copy-one-generation” is recorded in the residential gateway and stored as “copy-no-more”. The end-user experience may be inconsistent if the user starts watching live content still marked as “copy-one-generation” and then pauses and switches to the recorded version of the same content already remarked as “copy-no-more”.
Typically, a content service provider has full control of how many devices (e.g. STBs) there are in each home and charges the end user accordingly. When DLNA is used, the operator can deliver content to the residential gateway with no control over which and how many other playback devices the content can be distributed to within the home. DTCP-IP limits content streaming to the local proximity, thus preventing streaming over the Internet to remote locations. Despite DTCP-IP being limited to local content streaming, the operator cannot easily charge for each device (or at least add a percentage to the subscription for each additional device), nor charge a flat fee for content sharing within the home. The operator also does not know whether some devices are “traveling” between locations, potentially side-loading content that was not intended to be shared outside of the home (note that these devices could be legitimate DLNA/DTCP-IP devices, not hacked pirate devices).
Many content owners and service providers desire to limit the period of time a consumer can store a recording in the home. This is easily achievable with many traditional CAS and DRM systems, but DTCP-IP may not provide an adequate set of rights expressions to propagate these rules throughout the home. Similarly, and even more importantly, content recorded and stored in the home should expire when the consumer no longer subscribes to the service or channel. Again, once content “escapes” in the home network, albeit secure, the control the service provider has over such content may be very limited.